1. Field of the Invention
The present invention generally relates to linear motors and stage devices using the linear motors. More particularly, the present invention relates to a linear motor wherein heat from a coil is efficiently transferred and a stage device using the linear motor.
2. Description of the Related Art
In minute positioning devices used for semiconductor manufacturing devices, liquid crystal manufacturing devices, or the like, a linear motor is used as a driving part configured to drive a stage where a processed subject such as a substrate is mounted. Both ends of the stage are driven in translation by a pair of linear motors.
Such a liner motor includes a coil part and a magnet yoke part. Plural coils are arranged in a single line in the coil part. Plural permanent magnets are arranged in a single line state so as to face the coil line in the magnet yoke part. The coil part is energized so that an electromagnetic force is generated and a thrust force (driving force) is generated to the permanent magnet.
As a structure of the linear motor, there is a moving coil type and a moving magnet type. In the moving coil type, the magnet yoke part works as a fixing side and the coil part works as a movable side. In the moving magnet type, the coil part works as a fixing side and the magnet yoke part works as a movable side.
In either type, if temperature is increased due to heat from the coil, the resistance value of the coil itself is increased so that a driving current is reduced. In the linear motor, since the thrust force is proportional to the driving current, the thrust force is decreased as the driving current is decreased.
In addition, heat generated from the coil influences the external environment. Because of this, a cooling part is configured to cool the coil part in the linear motor in order to reduce the influence due to heat from the coil.
In the meantime, a linear motor having a structure where two coil lines face two magnet lines is suggested. A configuration of each of the coils is not a flat shape but a rectangular shape not having one side where both sides of a coil wound in a rectangular shape are bent at 90 degrees. In addition, arrangement directions of coils neighboring each other of the coil line differ by 180 degrees and bending parts of both sides of the coils are overlapped in a moving direction, so that torque change is prevented.
However, in the above-mentioned linear motor, the directions of the neighboring coils formed in a rectangular shape not having one side by bending both sides at 90 degrees differ by 180 degrees so that the bending parts of both sides of the coils are overlapped. Hence, while lack of torque is solved so that minute moving control is realized, it is not possible to insert the panel shape heat pipe in the gap between the coil lines bending in a crank shape.
Because of this, in the above-mentioned linear motor, a cooling flow path is provided so as to circulate a coolant to the coil part and a pump or the like is provided so as to supply the coolant to the cooling flow path. In addition, a sealing structure for preventing outflow of the coolant is necessary. Hence, the structure may be maximized and complex so that manufacturing cost may be increased.